Identifying geo-indicators of land degradation in a semi-arid Mediterranean environment using remote sensing

Radiometrically-calibrated Landsat TM data are combined with conventional observations (soil and geology maps, hydrogeological data) to analyze change in the land cover of the Los Monegros region of Aragon, Spain, over the period 1984-1997 in order to evaluate the effects of the extension of irrigation on the extent of arable agriculture. Linear spectral unmixing combined with a band ratio mask is used to determine proportions of individual soil types. A change detection technique: based on principal component analysis is used in order to identify areas that are most at risk from land degradation processes, principally increased soil erosion and soil salinization, and to explain the ways in which agricultural practices interact with the geomorphological and hydrogeological characteristics of the study area in inducing and maintaining the processes driving change.